Charge trapping and storage in SiNx thin films deposited with Oxford PlasmaLab 100 system

Negative charges in silicon nitride films are beneficial for surface passivation of rear side of p type solar cells.[1] Previous studies indicates that N-rich SiN_x films in an oxide-nitride-oxide structure display good charge trapping and storage ability. In this work, an Oxford PlasmaLab 100 PECVD system is used to vary the deposition conditions (temperature and RF power). SiN_x films deposited at 400°C and RF=60W show an initial negative charge density of 1.2×10¹³/cm² after negative charge injection. Modeling results suggest that tunnel oxide may not be necessary for achieving good charge stability, which will make the application more flexible.